190301a Hydraulic Principles

Question 1

What advantages does hydraulic control have?

Answer 1

Relatively compact, powerful but light, flexible installation, cooling and lubrication system is easy to accommodate, provides precise accurate and smooth implement positioning, easy to protect from overload conditions

Question 2

What are the disadvantages of hydraulic control?

Answer 2

Fluids under pressure are dangerous, noises produced, oil leakage is a source of contamination and fire, temperature variations affect reliability, air trapped in the system can produce poor operation and damage, they can easily operate inefficiently

Question 3

What is the primary function of a hydraulically controlled machine?

Answer 3

To perform useful work

Question 4

Define work

Answer 4

Force acting through distance

Question 5

How do you find force using a formula?

Answer 5

Multiply pressure and moving area together

Newtons X meters squared

Question 6

Describe force

Answer 6

Force is the push or pull that is capable of producing or changing the motion of a body

Question 7

As well as produce or change the motion of a body what else can force do?

Answer 7

Force must also be generated to retard or stop motion

Question 8

What are some types of energy?

Answer 8

Mechanical, hydraulic, heat, electrical, chemical, light, and sound

Question 9

What is energy? Define it

Answer 9

The ability to perform work usually in BTUs or Jules

Question 10

Briefly describe potential energy

Answer 10

Energy that is stored in a body or substance

Question 11

If a spring is compressed is it considered potential energy?

Answer 11

Yes

Question 12

True or false: the law of conservation of energy states that energy cannot be created or destroyed

Answer 12

True

Question 13

In an engine is combustion chamber is it true that chemical energy is turned into heat energy?

Answer 13

Yes it is true heat energy is created in the engine combustion chamber

Question 14

On an engine where is the mechanical output?

Answer 14

The flywheel

Question 15

What is considered wasted energy in an engine?

Answer 15

Heat and noise

Question 16

What type of waste energy does a hydraulic system have?

Answer 16

Heat energy

Question 17

What two states does energy exist in?

Answer 17

Kinetic and potential

Question 18

What does rate of oil flow have to do with the motion of our implements?

Answer 18

The rate of flow affects the speed of our implements

Question 19

What does potential energy always want to do?

Answer 19

Change to kinetic energy

Question 20

What is a good example of a potential energy storage in a hydraulic system?

Answer 20

An accumulator

Question 21

For our purposes do we consider oil or fluid compressible?

Answer 21

No

Question 22

A pressure difference shows a difference in potential energy what is it also called?

Answer 22

Pressure drop

Question 23

Bernoulli’s principle states what?

Answer 23

As velocity of a fluid decreases the pressure exerted by the fluid increases

Question 24

What did Bernoulli discover about constant flow’s and horizontal tubes?

Answer 24

The sum of the potential (pressure) and kinetic (rate of oil flow) energy would remain constant at any point along the length of the tube

Question 25

Is the velocity of liquid greater or less or in a small section compared to a wider section of pipe?

Answer 25

The velocity of a liquid in a small section is greater compared to the wider section

Question 26

Why do we get a higher pressure in a wide section of pipe compared to a small section of pipe?

One piece of pipe with large and small sections

Answer 26

The increased volume in the wider section of pipe allows fluid to slow down which reduces the amount of kinetic energy, the result is a higher pressure because there’s more potential energy available

Question 27

If you demand more force and speed what is required?

Answer 27

greater power requirements

Question 28

What is the formula to find pressure?

Answer 28

Force divided by area

Pressure = Force/ Area

Question 29

What is the formula to find flow rate?

Answer 29

Flow rate equals cylinder volume divided by time

Flow rate = cylinder volume / time

Question 30

What does flow rate determined in our cylinders?

Answer 30

Speed, the time required to raise load

Question 31

What type of measurement do we use to represent the amount of power that a cylinder must produce in order to raise a load in a specific time?

Answer 31

kW

Kilowatts

Question 32

What do we compare to find hydraulic system efficiency?

Answer 32

Output power is compared to the input power to drive the system

Question 33

What form of power losses can we have?

Answer 33

Pressure losses and flow losses

Question 34

Are hydraulic systems 100% efficient?

Answer 34

No

Question 35

What can affect laminar flow?

Answer 35

Abrupt changes in directions , abrupt changes in cross-section, conductors too small

Question 36

What must exist to allow flow to occur?

Answer 36

There must be a difference in potential energy

Question 37

What do we gain in laminar flow?

Answer 37

Lower fluid velocity and turbulence which result in a lower pressure loss and heat generation

Question 38

What does insufficient internal volume result in?

Answer 38

Excessive fluid velocity

Question 39

Disrupting laminar flow creates what?

Answer 39

Turbulence

Question 40

Describe backpressure?

Answer 40

Pressure created by resistance to flow on the return side of a system or component?

Question 41

In internal leakage a good thing or bad thing?

Answer 41

Good thing if it is not excessive?

Question 42

What does good internal leakage do?

Answer 42

Provides lube, seals and supports

Question 43

What causes internal clearances to increase?

Answer 43

Wear